This invention relates to a device for removing air from the space above the fluid in containers such as bottles before the closure device is applied to the container.
The invention is particularly applicable in cases where containers are filled with a foaming liquid, such as beer, where it is desired to remove the air above the liquid level before a crown closure is applied to the bottle. As is known, air may cause degradation of the beer in time and bring about a corresponding reduction in its shelf life. A known practice for removing the air from the unfilled neck of the bottles is to inject a medium directly into the bottle opening under pressure to thereby cause a controlled foaming of the contents of the bottle in which case the foaming displaces the air in the neck before closure. Typically, the pressurized injection medium may be sterile water, the filling liquid itself, carbon dioxide gas or other medium that is compatible with the particular fluid in the bottle. The new air removal device will be described in reference to filling beer bottles that are typical of those whose contents foam when a jet of carbon dioxide is directed into the bottle under pressure. The term "bottle" is understood to encompass other containers that are closed or capped after air is excluded.
It is very important to apply the cap within a specific time range after the air displacement medium is injected so air does not flow back in before the closure is applied. It is also important to avoid excessive foaming since this causes loss of fluid product and consequent lowering of the correct fill level as well as contamination of the closure device, while too little foaming action results in high air content of the product which in turn affects taste and shelf life as previously mentioned.
There are prior art devices for excluding air from bottles. One such device comprises an injector mounted on an arm that extends over a bottle that is being transported in the starwheel on the discharge side of a bottle filling machine. The injector is adjustable and can be set in various positions relative to the place at which the bottle closure is applied which, in effect, allows adjustment of the time between the air displacement medium injection and closure application. This manual timing adjustment is made by an operator for a certain product at the beginning of a filling operation and operates at maximum efficiency only for a single filling speed. If filling speed or bottle transport speed is increased, the duration of the injection becomes shorter and the foaming action inadequate. If, however, the filling speed is decreased, the duration of the injection becomes longer and the liquid product overflows. Therefore, the device just described only works at maximum efficiency at a single speed. Speed variations that commonly occur during normal operating conditions result in the deficiencies which were just described. As a consequence, it has been suggested to conduct the jetting operation at different pressure levels that automatically adjust to the speed of the bottle filling and closure application equipment.
Precise control of the foaming action over a wide speed range through pressure regulation, however, presents a problem due to the relatively small jetting orifice and low quantity of jetting medium used. It is further complicated by the chemical and physical interaction during the foaming process.
There is another prior art device for foaming of liquid in bottles to exclude air. In this device a jetting nozzle is mounted to a horizontal arm which is eccentrically adjustable to the axis of the starwheel on the discharge side of the filling machine. During equipment stoppages, the arm is located away from the bottles. Automatic synchronization of the varying equipment speeds is not intended nor possible since the jetting device is merely moved between its active and inactive position.